Extension tower for use with a fork lift truck



1961 E. A. CAMPBELL ETAL 2,966,956

EXTENSION TOWER FOR USE WITH A FORK LIFT TRUCK Filed Feb. 26, 1960 4Sheets-Sheet 1 IN VEN TORS 'RlV/N A. CAMPBELL BY #4 6. MAC/(ENZ/ r 7 pATTORNEYS Jan. 3, 1961 E. A. CAMPBELL EI'AL 2,966,956

EXTENSION TOWER F OR USE WITH A FORK LIFT TRUCK Filed Feb. 26, 1960 4Sheets-Sheet 2 IRMA J. (IA/ 861i Jan. 3, 1961 CAMPBELL EAL 2,966,956

EXTENSION TOWER FOR USE WITH' A FORK LIFT TRUCK Filed Feb. 26, 1960 4Sheets-Sheet 3 /&

IN VEN TORS FEM/V '4. CJMPBEZL 2,966,956 EXTENSION TOWER FOR USE WITH AFORK LIFT TRUCK Filed Feb. 26, 1960 Jan. 3, 1961 A. CAMPBELL EIAL 4Sheets-Sheet 4 mm m 0 WM ma r 4 MM m 5 BY M,

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United States EXTENSION TOWER FOR USE WITH A FORK LIFT TRUCK Erwin A.Campbell and Ian G. Mackenzie, Pittsburgh, Pa, assignors to Lee C. MooreCorporation, a corporation of Pennsylvania Filed Feb. 26, 1960, Ser. No.11,345

8 Claims. (Cl. 182-63) This invention relates to telescoping towers thatcan be raised and lowered, and more particularly to such a tower thatcan be transported and operated by a fork lift truck. Such towers may beused as scaffolding from the top of which work can be done on adjacentstructures.

It is among the objects of this invention to provide an extension towerthat does not include its own power machinery, that is especiallydesigned for movement from one location to another by a standard forklift truck, that uses the power of the truck for extending the tower,that is rigid and stable during use, and that is of simple andinexpensive construction.

In accordance with this invention a vertically exensible member issupported by a base, to which it is secured. The base extends away fromone side of the extensible member and is formed to receive and supportthe front wheels of a fork lift truck while the truck fork is besidethat member. Operativcly connected with the extensible member is meansfor extending it when said means is raised by the fork while the truckis on the base. Preferably, a platform projects from the side of the topof the tower opposite to the side from which the base projects. Withthis arrangement, when the extensible member is formed from a series oftelescoping vertical columns, antifriction guide means for the variouscolumns are located only at the upper ends of the columns beneath thelaterally projecting portion of the platform and at the lower ends ofthe columns at the opposite side of the tower.

The preferred embodiment of the invention is illustrated in theaccompanying drawings, in which Fig. l is a side view of the collapsedtower being transported by a fork lift truck;

Fig. 2 is a side view of the extended tower, with parts broken away;

Fig. 3 is a view of the front side of the raised tower;

Fig. 4 is an enlarged top view of the tower, with the platfrom absent;

Fig. 5 is a horizontal section through the collapsed tower;

Fig. 6 is a central vertical section through the collapsed tower withthe central portion broken away;

Fig. 7 is a fragmentary section taken on the line VII VII of Fig. 4; andv Fig. 8 is a diagrammatic view of the extended tower.

Referring to Figs. 1, 2 and 3 of the drawings, a vertically extensiblemember is formed from a series of hollow telescoping columns 1 to 6nested one within another, with the bottom of the outer column 1 rigidlymounted on a base 7. A ladder 8 may extend from the front end of thebase up to the top of the outer column. It is permanently secured inplace. The opposite or rear end of the base extends away fro-m thecolumns far enough to permit the front wheels of a standard fork lifttruck 9 to be run onto the base. The base may be formed from a pair ofparallel longitudinal beams 11 rigidly connected at their front ends by'a channel 12 and at their centers by a channel 13. So that the front endof the truck will zsaaass Patented Jan. 3, 1961 not be raised anappreciable amount when it is on the base, it is preferred to mounttread plates 14 at the outer sides of the long beams 11. These platesmay be secured to heavy tie rods 15 that extend through the beams. Theplates support the wheels of the truck.

The tower columns may be made in various ways, but it is preferred tomake each one in the same way as outer column 1, which, as shown inFigs. 4 and 5, is formed from two parallel side plates 16 connected attheir front and rear edges by angular plates 17 and 18 that are V-shapein horizontal section. The plate 17 at the front side of the towertapers forward and, in order to provide a space for a cable that is usedin elevating the tower, the rear side plate 18 preferably is tapered inthe same direction so that the column somewhat resembles an arrow inhorizontal section. Column 2, when in its lower position, seats on stops19 resting on the base and welded to the front wall 17.

Mounted on top of the inner column 6 is a suitable load support, such asa platform 21 shown in Figs. 1, 2 and 3, that may be provided at itscorners with sleeves 22 in which the corner posts 23 of a railing areslidably mounted. While the tower is collapsed, the railing is in alowered position relative to the platform, as shown in Fig 1. Before orafter the tower is raised, the railing can be pulled up through thesleeves until spring latches 24 snap out over the top of the sleeves tosupport the railing in operative position.

To guide the tower columns in their vertical movements, antifrictionmeans are provided, preferably in the form of rollers. Thus, as shown inFigs. 4 and 6, mounted in brackets 26 on top of the front side of eachcolumn, except the inner column, is a pair of guide rollers 27 that willbe engaged by the angular sides of the front wall of the next smallercolumn as the tower is extended. It will be seen that each two rollersprevent movements of the adjoining column forward and laterally. For areason that will appear presently, guide rollers are unnecessary at thebottom of the front walls and the top of the rear sides 18, but similarguide rollers 28 (Figs. 5 and 6) are mounted in brackets 29 attached tothe bottom of the rear side of each column, except the outer column.These bottom rollers are engaged by the adjoining column as the tower isextended.

By projecting the platform forward from the top of the inner or uppercolumn as shown in Fig. 2, the weight of a man on the platfrom will tendto tilt the extended tower forward. This will press each column forwardagainst the upper guide rollers 27 in front of it and backward againstthe lower guide rollers 28 behind it, so further guide rollers are notrequired. This is a big advantage, because it means that the columnswill tightly engage all of the guide rollers and thereby avoid slack orplay in the tower. If guide rollers had to be located at all fourcorners of each column, as would be the case if the loading on the towerwere symmetrical, clearances would be required that would result inlateral movements of the columns as the man on the platfrom moved about.That would make the tower unstable and dangerous to use. Nevertheless,aligners in the form of lugs 30 may be welded to the front walls of thecolumns near their lower ends, and lugs 31 may be welded to the rearwalls near their upper ends. They normally do not touch theadjoiningcolumns, but will prevent any column from tilting backwardly amaterial amount accidentally.

in order to elevate or extend the tower, it is preferred to use cablemeans that include a lower cable 33, the outer end of which is attachedto means, such as a horizontal bar 34, that normally rests on spacedsupports 55 near the bottom of the back of the columns. When the forklift truck is driven onto the base with the fork 36 in its lowerposition, the fork will move forward beneath the ends of the bar andstraddle the columns. By then elevating the fork in the usual way, itwill lift the bar and that will pull on the cable and lift columns 2 to6. This is because the cable extends from the bar down around a sheave37 mounted near the bottom of the tower, up and over a sheave 38 mountedon top of the outer column, then down between the outer column and thenext smaller one as shown in Figs. 6 and 8, across column 2 beneathsheaves 39 suspended from its bottom, and then up again between theouter column and the next smaller one to an anchor at secured to columnll near its top. When the lifting bar is raised by the fork, the lengthof cable inside the outer column is shortened and that raises the restof the columns.

At the same time, the remaining columns rise up out of one anotherbecause sheaves are mounted on their upper ends near their backs andsupport cables, each of which has its outer end secured to the upperpart of the next larger column and its inner end secured to the lowerend of the next smaller column. Since there is not enough room to placeall of the sheaves in the same plane, two sheaves 42 are mounted oncolumn 2 on opposite sides of sheave 38. They support cables 43. Asingle sheave 44 is mounted on column 3 and supports cable 45. Twosheaves 46 beside sheave 44 are journaled on column 4 for supportingcables 47. Finally, one sheave 48 on column 5 carries cable 49, theinner end of which is secured to the lower end of inner column 6. Aseach sheave is moved upward by its supporting column, that sheave causesthe inner end of the cable over it to raise the next smaller column.Therefore, by raising the lifting bar only far enough to elevate thesecond column 2 in the bottom one, all of the rest of the columns willlikewise be elevated simultaneously relative to one another as shown inFigs. 2, 3 and 8. In one specific example, a telescoping tower that isonly about seven feet tall when collapsed, can be extended in thismanner to a height of thirty-five feet.

After the tower has been lowered by lowering the truck fork and liftingbar 34, the truck can be backed off the tower base and then run forwardagain a short distance with the fork at a lower level to project itsfront end through loops 51 that are secured to the base. The entiretower then can be lifted from the ground by raising the fork as shown inFig. 1. The loops are in such a position on the base that the tower willtend to tilt forward, but that is prevented by the rear end of the baseengaging the bottom of the fork.

The extension tower disclosed herein can be used anywhere a fork lifttruck is available for moving it and furnishing the power for raisingit. Therefore, a special power plant for the tower does not have to besupplied, which reduces the weight and cost of the apparatus. The truckoperator can pick up the tower, without leaving his seat, and transportit to another location. Also, he does not need to leave his seat inorder to set the tower down again, apply the weight of the truck to thetower to steady it and then raise it to any desired height.

According to the provisions of the patent statutes, we have explainedthe principle of our invention and have illustrated and described whatwe now consider to represent its best embodiment. However, we desire tohave it understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically illustratedand described.

We claim:

1. An extension tower comprising a base, a vertically extensible membersupported by the base and secured thereto, said base extending away fromone side of said member and formed to receive and support the frontwheels of a fork lift truck while the truck fork is adjacent saidmember, and means operatively connected with said member for extendingit when said means is raised, said means being adapted to be raised bysaid fork while the truck is on the base.

2. An extension tower comprising a base, a vertically extensible membersupported by the base and secured thereto, said base extending away fromone side of said member and formed to receive and support the frontwheels of a fork lift truck while the truck fork is adjacent saidmember, cable means operatively connected with said member for extendingit upon pulling the cable means, the cable means including a cablehaving an outer end near said base, and means connected to said outerend of the cable adapted to be raised by said fork while the truck is onthe base to thereby pull the cable means.

3. An extension tower comprising a base, a vertically extensible membersupported by the base and secured thereto, said base extending away fromone side of said member and formed to receive and support the frontwheels of a fork lift truck while the truck fork is straddling saidmember, cable means operatively connected with said member for extendingit upon pulling the cable means, the cable means including a cablehaving an outer end near said base, and a horizontal bar connectedcentrally to said outer end of the cable adapted to rest across saidfork and be raised by it to pull the cable means.

4. An extension tower comprising a base, a vertically extensible membersupported by the base and secured thereto, a platform secured to the topof said member and projecting from one side of it, said base extendingaway from the opposite side of said member and formed to receive andsupport the front wheels of a fork lift truck while the truck fork isadjacent said member, and means operatively connected with said memberfor extending it when said means is raised, said means being adapted tobe raised by said fork while the truck is on the base.

5. An extension tower comprising a base, a nest of telescoped columnssupported by the base, means rigidly securing the bottom of the outercolumn to the base, a platform secured to the top of the innermostcolumn and projecting forward from it above the other columns, said baseextending away from the back of said outer column and formed to receiveand support the front wheels of a fork lift truck while the truck forkis beside the columns, means operatively connected with said columns forextending the tower when said extending means is raised, said extendingmeans being adapted to be raised by said fork while the truck is on thebase, antifriction guide means supported by the upper end of the frontof each column except said innermost column and engageable by the frontof the next smaller column as the tower is extended, and antifrictionguide means secured to the lower end of the back of each column exceptsaid outer column and engageable with the back of the next larger columnas the tower is extended.

6. An extension tower comprising a base, a nest of telescoped columnssupported by the base, means rigidly securing the bottom of the outercolumn to the base, a platform secured to the top of the innermostcolumn and projecting forward from it above the other columns, said baseextending away from the back of said outer column and formed to receiveand support the front wheels of a fork lift truck while the truck forkis beside the columns, means operatively connected with said columns forextending the tower when said extending means is raised, said extendingmeans being adapted to be raised by said fork while the truck is on thebase, each of said sections having opposite sides connected by front andrear walls V-shape in horizontal section, a pair of rollers supported bythe upper end of the front wall of each column except said innermostcolumn and engageable by the converging sides of the front wall of thenext smaller column as the tower is extended, and a pair of guiderollers secured to the lower end of the rear wall of each column exceptsaid outer column and engageable with the converging sides of the rearwall of the next larger column as the tower is extended.

7. An extension tower comprising a base, a nest of telescoped columnssupported by the base, means rigidly securing the bottom of the outercolumn to the base, said base extending away from one side of said outercolumn and formed to receive and support the front wheels of a fork lifttruck while the truck fork is adjacent the columns, a sheave mounted atthe top of one side of said outer column, a second sheave mounted belowsaid first mentioned sheave near the base, a cable extending around thebottom of the base sheave and then up and over the first sheave and downbetween said outer column and the next smaller column, means operativelyconnecting the cable with the lower part of said next smaller column,means connected to the outer end of said cable and adapted to be raisedby said fork to thereby pull the cable and elevate said next smallercolumn in said outer column, a sheave mounted at the top of each of theother columns except said innermost column, and further cables havingtheir inner ends connected with the lower parts of said other columns,each further cable extending up and over the sheave on the next largercolumn, and means connecting the outer end of each further cable to theupper part of the next larger column, whereby when said next smallercolumn is elevated the other columns will be extended out of oneanother.

8. An extension tower comprising a base, a vertically extensible membersupported by the base and secured thereto, said base extending away fromone side of said member and formed to receive and support the frontwheels of a fork lift truck while the truck fork is adjacent saidmember, means operatively connected with said member for extending itwhen said means is raised, said means being adapted to be raised by saidfork while the truck is on the base, and means secured to the tower nearits bottom for receiving said fork when the truck is not on said base,whereby the entire tower can be lifted up by the fork for transportationto another location.

References Cited in the file of this patent UNITED STATES PATENTS163,580 Covel et al. May 25, 1875 470,112 Ehrentraut Mar. 1, 1892533,667 Pokerny Feb. 5, 1895 2,598,730 Thompson June 3, 1952 2,705,083Soderstrom Mar. 29, 1955

